Firewall/NAT

Hey,
I'm a bit of a noobie at "complex" setups but here's my problem, if anyone can help I'd be hugely grateful as this is causing me a major headache.

We have 2 servers, BOX1 & BOX2, as well as m0n0wall installed on an old old box doing nothing but m0n0wall.

On BOX2 we have email and web server, on BOX1 we have our version control software, the problem is, until last thursday everything was on the single box, anyway, our version control software also uses port 80, as does our web server (apache 2.2.4) on BOX1.

How can I get it so that e.g.

VCS.DOMAIN.COM:80 will work correctly on BOX1 and,
ANYTHINGELSE.DOMAIN.COM:80 will work correctly on BOX2

Currently domains are setup correctly under DNS forwarding, however under Firewall RULES and NAT, both point port 80 to BOX2, is there a way I can get port 80 to point to both boxes!? or is that not the solution.

Thanks for this, my MD is going crazy at me for not finding this our before we installed the new box, so anything you can help with would be great.

Cheers.

you could use external port 81 for the 2nd machine
(and maybe forward the specified requested domains on your webserver to port 81 on the other server)

Don't think that'll work, as the Version Control Software' port usage is NOT configurable, you'd think for the price we paid for it it would be...

There must be some way to do it, E.G. a further rule that says ...

If incoming domain request eq VCS.DOMAIN.COM:80 then point to BOX1 else BOX2